Classical and molecular cytogenetic methods in diagnosis of a rare translocation t(3;21)

We report the characterization by traditional cytogenetic methods and fluorescence in situ hybridization (FISH) of a rare balanced reciprocal translocation t(3;21) in a male spouse connected with several miscarriages. G- and C-banding analysis of the male karyotype was suggestive of breakpoints in chromosomal bands 3q11.1 and 21p11.1. Multicolor-FISH analysis using chromosome-specific alpha-satellite probes in combination with a locus-specific bacterial artificial chromosome (BAC) from 21q22.3 allowed us both to identify the origin of centromeres in the derivative chromosomes and to establish centromere-telomere orientation of the translocated chromosome 21 segment. Characterization of the translocated chromosomes by FISH analysis permitted describing the exact karyotype of the carrier as: 46,XY,-3,-21,+der(3)(21qterO21q11. 2::3p11.2O cenO3qter),+der(21)(3pterO3p11.2::21q11.2OcenO21pte r).